The present invention relates to the general field of flow conditions for fluid transport pipes. It relates more particularly to a flow conditioner for a gas transport pipe, the conditioner including at least one flow rectifier associated with a porous plate located upstream from the flow rectifier.
The spinner gas volume meters that are installed in delivery stations are sensitive to conditions of use. In particular, when such meters are installed downstream from expanders or from obstacles such as valves, bends, double bends, constrictions, T-junctions, or other non-rectilinear elements, their accuracy can be affected by the disturbances generated by such obstacles.
In order to eliminate those disturbances, it is known to provide spinner meters with flow conditioners. Such equipment serves to attenuate the flow disturbances such as rotation of the gas stream, known as “swirl”, jet effects, or acoustic pulses, over distances that are short compared with the very long straight lines that are normally needed for natural attenuation.
Numerous types of flow conditioner exist that are capable of reducing the swirl of the gas stream. Such conditioners essentially comprise a perforated plate having a set of holes distributed in a plurality of concentric rings centered on the center of the perforated plate.
Nevertheless, very few conditioners reduce in satisfactory manner the swirl of the gas stream, its asymmetry, and the pulses in the flow. They are designed to be used with straight line lengths upstream and downstream that correspond to several times the nominal diameter of the pipe, which makes them of limited usefulness when it is desired to make compact expander and metering stations.
Furthermore, in order to make disturbances while reducing the size of such stations, the Applicant has proposed a flow conditioner as described in French patent application FR 2 776 033. In one of the embodiments, the conditioner comprises a perforated plate and a porous plate that is placed upstream from the perforated plate and that is put into contact therewith so that all of the gas flow passes through both elements. The presence of a porous plate in the conditioner is particularly advantageous since it makes it possible significantly to improve the homogenizing ability of the perforated plate on the flow.
Nevertheless, there exists a risk of the porous plate in such a flow conditioner becoming clogged, which would lead to a large increase in head loss, and above all to an interruption in gas feed continuity. Such clogging could arise in exceptional manner, in particular when the impurities present in the gas close up the pores in the porous plate.